I have to disagree.
After reading all the answers and thinking about it i can say that concentration in itself may not be so bad an idea. But it should not stay the way it is. What a system like this needs is consistency. If you compare spells and wonder why one needs concentration and the other does not, something is not right. That maybe put a bit too simplistic
but i hope you get what i want to say.
If you have spells that are very similar in what they do and how they work but one needs concentration and one does not then that will surely lead to questioning.
As @Leuenherz says, there is consistency in spells that require concentration but it is due to spell strength and ways of naturally ending the spell effects, not how similar in effect/class the spells are.
Concentration is a balance mechanic, not an immersion mechanic.
As of now the amount of concentration checks seems way too high. I really would rename it to "maintain". In a way that it needs magical energy constantly poured in to keep it active. So that falling prone and other little diversions can be ignored and conc. checks for this can be removed and you just need to check when someting really impacts the caster.
Falling prone should
not break conc according to 5e. This is a thing Larian 100% needs to change. This will make conc spells so much better.
And they do have a "maintain" mechanic: concentration :P
I'm slightly in favor of @SaurianDruid's idea that small amounts of damage don't break conc. But then would magic missile not break conc, since each missile can do only 2-3 damage? If so, this strongly nerfs it...this idea should only be implemented if Larian adds Shield as a proper reaction.
Edit: Actually, I have the ^ backwards. Magic missile damage (if 2 or 3) not breaking conc could be
instead of implementing Shield. Though obviously implementing Shield and proper reactions is better than this fix.
